How do greenhouse gases interact with incoming solar radiation?

• A. They absorb solar radiation directly
• B. They are transparent to certain types of incoming solar radiation
• C. They reflect all solar radiation
• D. They block solar radiation by scattering

Answer: (B)

Greenhouse gases largely let sunlight pass through. The Sun’s energy that reaches Earth is mostly in the visible range, and greenhouse gases are largely transparent to those wavelengths, so most of that incoming solar radiation goes through the atmosphere to warm the surface. What they do absorb is the infrared radiation the Earth emits after heating up, and they re-radiate that heat in all directions, including back toward the surface. This heat-trapping effect is what keeps the lower atmosphere warmer. So saying they are transparent to certain types of incoming solar radiation reflects that they don’t block or absorb most of the Sun’s energy directly, while still explaining why they heat the planet by absorbing infrared afterward. The other options describe absorption, reflection, or scattering of sunlight in ways that aren’t how greenhouse gases primarily operate.